I just replaced my bathroom vanity top. After installing drain in sink and setting vanity top I realized that the drain pipe does not line up with the pipe it needs to connect to unerneath sink. Ican't position sink to match up. What do ineed to do to the pipes under sink now?

We can't see it what dimension or how much it's off or what kind of pipe is off, so all I can say at this point is use a 22 1/2 degree elbow and/or some type of flex fitting.

Usually , trap has bit of left/right swing movement that will compensate for slight misalignment of new sink drain. Unscrew nut that holds trap together, swing trap to reach new drain and connect.

If this adjustment won't do, than you will have to either use flexible drain connector or rework your drains from scratch.

I just replaced my bathroom vanity top. After installing drain in sink and setting vanity top I realized that the drain pipe does not line up with the pipe it needs to connect to unerneath sink. Ican't position sink to match up. What do ineed to do to the pipes under sink now?
If you have the room they make a flexible tailpiece,(see image) and that coupled with the trap swing might just do the job for you. Good luck, Tom